“I’m The Only One” singer Melissa Etheridge and her partner of four years, “Nurse Jackie” creator Linda Wallem, said “I do” at the San Ysidro Ranch in Montecito, Calif., on May 31- just two days after their joint 53rd birthday.

“They were so happy,” a guest told People, adding that the musician serenaded her new wife with an original song. “It was really beautiful.”